Proximal Ir-Ir Cooperativity for Reprogramming the CO₂-to-DMF Hydrogenation Pathway

Area of Science:

• Organometallic Chemistry
• Catalysis
• Sustainable Chemistry

Background:

• The hydrogenation of carbon dioxide (CO2) to N,N-dimethylformamide (DMF) is crucial for chemical synthesis.
• Mononuclear catalysts face kinetic challenges due to the need for concerted substrate transformation.

Purpose of the Study:

• To develop highly efficient catalysts for CO2 hydrogenation to DMF.
• To overcome the kinetic limitations of single-site catalysts using multimetallic cooperativity.

Main Methods:

• Design and synthesis of binuclear Cp*Ir(III) complexes with ligand-enabled proximity.
• Utilizing computational and spectroscopic studies (in situ NMR, IR) to elucidate reaction mechanisms.
• Investigating the role of secondary coordination sphere effects (e.g., hydroxyl pendants).

Main Results:

• The optimized binuclear catalyst achieves a turnover number of 1,540,000 with >99% selectivity for DMF production.
• The binuclear architecture facilitates concerted substrate activation, lowering the reaction barrier.
• Experimental and computational data validate a low-barrier pathway involving dual-metal cooperation.

Conclusions:

• Binuclear iridium complexes with strategic ligand design enable efficient and selective CO2 hydrogenation to DMF.
• Multimetallic cooperativity and secondary coordination sphere effects can overcome intrinsic kinetic limitations of mononuclear catalysts.
• This work provides a new strategy for designing advanced catalysts for sustainable chemical transformations.